Reviewing through your description, there are a couple of places in your admin console where a max file size can be set, depending on how they are being added. As such, I would suggest checking the following places in your admin console:

However, if these are all set to greater than 2MB and you are still seeing the behavior, I would recommend submitting a case in your customer group as a next step ( MyJive Secret Support Group Administration FAQ ), so that a member of our support team can further review through your specific instance. When submitting the case, the following information should assist them with their investigation:

1. Is this limited to the specific file attached, image files in general or all files greater than 2MB?

2. Does the behavior occur in all places in your instance, or is it limited to a specific space/group/project?